The object of the system according to the invention is to achieve both a high operating rate and a high level of flexibility, on automatic equipment fed by a conveyor of the free transfer type. This equipment is found notably in series assembly workshops.
A general feature of this equipment is that it is composed of:
a lift and carry module which presents and accurately locates the product being assembled successively on a certain number of workstations. This module operates in conjunction, upline and downline, with conveyors of the free transfer type, which feed it and clear it, and which provide the links between a given equipment unit and the neighboring equipment units belonging to one and the same production line. PA1 a certain number of working modules equipping the workstations supplied by the lift and carry module, and corresponding to the operations involved in the production process. These operations fall into three major categories: PA1 component pick and place PA1 operations implementing a given technological process: welding, crimping, machining, screwing, etc. PA1 checking operations. PA1 production rate, made necessary by the increased volumes and the aim of reducing unit costs, PA1 flexibility, imposed by the diversity of market requirements which make it necessary to create a large number of alternative versions of a given product, and the requirements of modern management which aims to reduce stocks, and therefore to manufacture these alternative versions in small batches. PA1 generation of movements by a mechanical-type technology, notably using cams. PA1 development of a machine made up of modules which are mechanically independent from one another, each module having its own individual motor, synchronization of the overall assembly being performed by electronic means. PA1 a certain number of moving parts, corresponding to the functions to be carried out, PA1 a camshaft driving these moving parts, and comprising as many cams as there are movements to control, PA1 and a motor driving this camshaft via a suitable transmission system, making it perform cycles in an intermittent or continuous manner, as set out above. PA1 lifting the palettes supplied by an upline conveyor. PA1 carrying the palettes successively to the different workstations, at the required rhythm and with the accuracy required, PA1 removal of the palettes on a downline conveyor. PA1 to lift all the palettes and move them one step when downline travel takes place, PA1 to return empty when upline travel takes place, this phase being the one during which the palettes are stopped on the work-stations, and therefore able to receive the corresponding process operations. PA1 upward movement, in the course of which the rule picks up all the palettes present on the stations, plus the one which is against the stop on the upline conveyor, PA1 horizontal transfer one step downline, PA1 downward movement, in the course of which the palettes are placed on the workstations, except for the last one which is placed on the downline removal conveyor, PA1 horizontal return upline, empty, a phase during which the working operations can be carried out.
In some cases, the manufactured product can be directly transported via the conveyors to the machines. More often than not, it has to be placed on functional palettes. Although the invention is applicable to both cases, it will be assumed in the following description that the system comprises palettes. The present evolution of products and management methods results in the need for high performances in two fields in particular:
There are at present no machines on the production equipment market with high performance ratings in both these fields.
Air-operated machines, traditionally the most common, are slow (usual operating rate about 1000 cycles per hour). They do however enable the operating sequences to be easily adapted, which gives them a useful flexibility potential.
A second family of machines is constituted by mechanical machines with cams, organized around a central drive system which drives all the modules (lift and carry and working modules) by means of a common transmission system. These machines reach high operating rates (2000 to 3000 cycles per hour) but their operation is extremely rigid due to the fact that all their movements are mechanically interconnected. Their flexibility potential is therefore very low.
The purpose of the present invention is to define a principle of a machine which will combine the advantages of speed and flexibility, as well as a certain number of constructive arrangements relating to this type of machine.